The present invention relates to a powered oscillating hand tool comprising a drive unit having an electric motor with a drive shaft to which a sander head can be attached. In general, known sanders can be described as either random orbit sanders or orbital sanders.
In random orbit sanders, a circular platen is driven by a drive system which comprises an eccentric bearing so that the platen can spin independently of the motor, and the platen describes a random orbit. Such sanders are in general used for the removal of relatively large quantities of material. Alternatively, the sander may be of the orbital type, with a shaped shoe, the drive system of which comprises an eccentric which is restrained so that the sander shoe cannot spin independently of the motor and it therefore describes a regular orbit. The shoes of such sanders are available in a range of shapes and such sanders are in general used for the removal of relatively small quantities of material, for example for detailed work or for finishing. By choice of a suitably shaped shoe, it is possible to access areas which are inaccessible with a random orbit sander. The fixed eccentric drive system of the orbital sander is cheaper and simpler to manufacture than the eccentric bearing of the random orbit sander.
Known sanders have been either of the random orbit type or the orbital type, which has meant that when the user wished to have the ability to perform both coarse and detailed sanding operations, it has been necessary for him to purchase two separate units, one of each type, or to purchase only one unit and suffer the disadvantages thereof.
It is an object of the present invention to provide a sander in which the above disadvantages are reduced or substantially obviated.